EdM, RickS

During a PSL team telecon this morning, we decided not to try to operate the HPO until we can open the housing and inspect optical surfaces next week.

We decided to use this time to get the Diagnostics Breadboard up and running.

JimB updated the paths on the PSL ante-room workstation (pslws0)  so we could run it from there.

The HPO was disabled so it could not be started accidentally: currents set to zero (for nominal values, see photo below.  Note that they were increased by 1A during our investigations last night), DB power supplies switched off, DB power supply power cords disconnedted from back of units.

We closed the internal shutter in the HPO and switched on the Front End.

We adjusted the attenuator at the output of the HPO to minimize the power directed to the PMC (directed all of it to the power meter).

We then proceeded with the DBB measurements, following the detailed procedure in T1400730-v1.  We wanted to at least walk through the measurements to make sure everything with the DBB is functioning.

The RPD DC level is only 8.28 V.  Nominal is 9-11 V.  The power in this path is already optimized externally (we didn't open the DBB).  We proceeded with the measurement.

The RPN results are in: /ligo/lho/data/psl/psl_noisereports/2016-04-29/dbb_rpn-002.pdf and .zip  RPN is a bit above the nominal levels (factor of 2).  The fans in the laser room, and lights, are on.

The PMC locked locked without intervention in ~30 seconds.  We ran a CALI_ERRSIG calibration on the dither lock error signal.

The frequency noise (FRQ) scan results are in:  /ligo/lho/data/psl/psl_noisereports/2016-04-29/dbb_frq-001.pdf and .zip Huge peaks at 10 Hz and harmonics.  Something not right here.

We proceeded to the pointing (PNT) measurement.  We calibrated the QPDs. /ligo/lho/data/psl/psl_noisereports/2016-04-29/dbb_pnt-001.pdf and .zip Again, big peaks at 10 Hz and harmonics.

Proceeded with the modescan (MSC) measurement.  Results in /ligo/lho/data/psl/psl_noisereports/2016-04-29/dbb_msc-002.pdf and .zip The report shows 4.1% higher order mode power, which looks good if it can be trusted.

In summary, the DBB seems to be operational.  Some tweaking might be necessary to bring it to full usefulness, but it is working and the instructions for running it, along with the user interface, are very good.

Peter and I decided to leave the laser running in this state (FE only) rather than switch it off.  There is almost no light (< 1mW) directed toward the PMC.  The DBB shutters are closed, with the system in standby.